Alternating-current-motor control.



, Elf. WJALEXANDERSON. ALTEENATING CURRENT MOTOR CONTROL.

APPLIOATION FILED JAN.6.1910.

Patnted June 2, 1914.

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ATTURNE'K E. F. W. ALEXANDERSON. ALTBRNATING CURRENT MOTOR CONTROL.

APPLIOATION FILED JAN.6,1910.

1 ,O98,656. Patented Jul- 9 2, 1914,

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BY ZZW M421 H15 Arraazszpr.

' UNITED sTATEs PATENT OFFICE;

ERNST I. WuALEXANDERSON, 0F SCHENECTADY, NEW YORK, ASSIGNOR T0 GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW'YORK.

T 0 all whom it may concern Be it'knownthat I, E NST F. W. ALEX- ANDERSON, a citizcn'of t e United States, residing at Schenectady, county of Schenectady, State of New York, have invented -ce'rtain new and useful Improvements in three-phase motor is especially suitable. For other kinds oflservice, as in yards where switches and cross-overs are numerous, three phase operation may be objectio'nable, because of the difliculty of properly' installing twotrolley wires or working conductors in such locations. A control arrangement whereby the motors may be operated on either single-phase or poly-phase" currents,so that in the yards and terminals.

single-phase currents-may be employed, and on the inain line,thre'ephase currents, presents great advantages in many cases.

My invention consists in providing such a control; of the motors by providing their rotor windings both with commutators and colle'c oi rings, with means for establishing .tions for the stato'rwindings of the motors and establishing the rotor circuits through the colnmutators for single-phaseoperation,

and with means for establishing in a special manner poly-phase connections of the stator winding and es ablishing the rotor circuits through'the c0 lector rings-for poly-phase operation,

My invention further comprises an galran e ent whereb the supply transformer win in B have their connections changed in a. simp e and eflicient manner when the motor connections are changed as above spec1- My invention will be best understood by Specification of Letterslaten t. Application filed January e, 1910. Serial No. 536,656.

ALTERNATING CURRENT-MOTOR CONTROL.

Patented June 2, 1914.

reference-to the accompanying drawings, in which- Fi re 1 shows diagrammatically a pair of a ternating current motors and transformer windings for supplying themprovided with a transfer switch, arranged in accordance with my invention, for connecting the motors and transformer windings for single-phase or oly-phase operation; Fig. 2 is a diagram of the connections established by the transfer switch of Fig. 1 for single-phase operation; Fig. 3 is a. simplified diagram, corresponding to Fig. 2, with but only onemotor shown; Fig. 4 is a diagram o f-the connections established by the trans fer switch of Fig. l for three-phase operation, and Fig. 5 1s a simplification of Fig. 4 showing only one motor.

In the drawings, A and A represent the rotor windings of a pair of motors each proyided with commutator and collector rings.

The motors are provided with stator windings B and B,respectively,- and also with windings C and C, which are displaced electrically 90 degrees from the windings B and B. i

D and D represent transformerwindings for supplying current to the motors;

-'E and E represent resistances used in poly-phase operation. y if F represents a transfer or. commutating switch for changing the motor connections from single-phasc to poly-phase." This switch is shown diagrammatically with its contacts developed on a plane surface enibodying 26 contact fingers and two sets of movable contacts. In order to simplify the drawing the other controlling switches ordinarily employed are omitted.

For single-phase operation the switch F of Fig. l is'moved so as to bring the lefthand'row of movable contacts into engagement with the contact fingers. When this is done. the connections of Fig. 2 are established. The left-hand terminalsof the transformers D and I) are connected together zit-fingers 7 and 8 and the right-hand terminal of transformerwinding D is connected to ground at fingers 1 and 3, so that cuits orthe collector rings are open at fin- I gers 19, 20, 21 and 22 for rotor A and fingers 23, 24, 4 5 and 26 for rotor A. The connections thus established may be shown in simplified form for a single motor, as in Fig. 3. It will be seen that the armature winding is short-circuited so that the motor acts as a repulsion motor, the windings B and C be-? ing connected in series with each other and,

acting as inducing and exciting windings respectively. By inducing windlng I- mean a winding producing 'amagneto-motivc force .along the-line of the commutator-f brushes. In Fig. ings- B and B with each other as are windings C and C.

For three-phase are connected in par 2 the compensating wind-f allel, also the exciting;

operation on switch F is moved to its pther "position thereby estab-, lishing the connections shown in Fig. 4;. The; ri 'ht-hand terminalof transformer winding is connected to the middle terminal of? windin D through fingers 1 and 2, thereby; establis ing the well known T connectiomi whereby the transformer windings are, adapted for connection to a three-phase supply through the trolleys- The upper tcrmi-; nals of windings B and Bare now connected through fingers 9 and 5 to the contact d on transformer winding D. These wind-- ings are thus connected in arallel across a variable'portion of the wlndm of transfouner D. The middle terminals of these two windings B and B are connected:

through contacts 13 and 12 to the right-hand terminal of winding C, the left hand termi. 'nal of which is connected through contacts- 14 and 10 to the right-hand terminal of winding C, the left-hand terminal of which:

is connected through contacts 11 and 4 to the movable contact d on transformer winding-D. The two windings C- and C are thu connected in series between the middle terminals "ofthe windin s B and B and a point on winding D. T is, as is best shown in Fig. 5, establishes a T connection of the stator windings of the motors correspond: ing to the T connection of the transformer windings and adapting the stator connections for three-phase operation. The circuit -rent motor for 0 of the commutator brushes is opened at contacts 15 and 16 for rotor A and 17 and 18 for rotor A, while through the collector rings the -rotor winding A is connected through contacts 19 to 22 inclusive to resistances E, and the rotor Winding of A is connected through contacts 23 to 26 inclusive to resistances E. The rotor windings are thus short-circuited through'variable resistances, as in the ordinary induction motor operation, the connections, simplified for a single motor, being as shown in Fig. 5.

It has already been pointed out that with the single-phase connections shownin Fig. 2

the exciting windings C and G of the two motors are connected in parallel. With the poly-phase connection shown in Fig. ithese windings are connected in series. The reason for this is that the exciting winding of a single-phase commutator motor has a much smaller number of turns than the compensiting winding, but by putting the two exciting windings of the'motors'in series while the inducing windin are maintained in {parallel the ratio of t e number of turns in the two circuits may be made approm'matel correct for three-phase operation with the connection shown.

I- do not desire to limit myself to the particular connections and arrangements of parts shown and described, but aim in the appended claims to cover all modifications which are within the scope of: my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is 1. In combination with an alternating cur ration on both singlephase and three-(plume currents, a pair of transformer win motor, means for connecting sald windings in parallel and connecting said motor as a single-phase commutator motor and to said windin and means for establishing a T gs for supplying said connection 'for said and connectmg said motor as a oly-phase induction motor and to said, win in 2. In combination wit an alternating current motor haying a rotor windingpro vided with both? commutator and collector 1 rings, a lurality of transformer windin for supp yin said motor, means for esta lishin trans ormer windings and the stator windsing e-phase connections for said ing of said motor and connecting together said windings and establishing the rotor.

circuit through the commutator, and means for establishing poly-phase connections for the transformer and stator windings and connecting together said. windings and; esthrough the coltablishing the rotor circuit lector rings.

3. In combination with s in of alternating current motors each having a rotor winding provided with both commutator and co] ector rings and two stator windings displaced from each other by ninety eiectrical degrees, means for establishing the rotor 5 circuits through the commutators and connecting the stator windings of each motor as inducing and exciting windings respec- V tively', the excitingwindings of the two mo tors bein connected in'parallel, and means 10 for estab ishin'g the rotor circuits through 

